Difference between revisions of Presbyopia

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Presbyopia is the hardening of the [[lens]] in the [[eyeballs]] such that it becomes difficult to see [[near work]]. This is common in older adults and is commonly treated with [[reading glasses]] or [[bifocals]].

Presbyopia is the hardening of the [[lens]] in the [[eyeballs]] such that it becomes difficult to see [[near work]]. This is common in older adults and is commonly treated with [[reading glasses]] (reduced minus for myopes), progressive lenses, or [[bifocals]].

==Correction==

As you age, the lens in your eye becomes less flexible. This makes [[accommodation]] more difficult and brings on "arms are not long enough to read" symptoms. Someone may be both [[myopic]] and presbyopic, and have deficits in both near and far vision. Your [[Prescription]] will have an "Add" section specifying bifocals or multifocals if you have diagnosed presbyopia, or if your doctor thinks it best to reduce eye strain.

===Two glasses===

It is an option to have two pairs of glasses, one for close-up, and one for distance, instead of trying to combine both near and far corrections in one pair of glasses.

===Bifocals===

Glasses with a lower section that is specifically for close work.

===Progressive lenses===

Glasses with a gradient from zero to near plus addition spherical power from top to bottom.

===Multifocals===

Contacts that have sections for near and far work, which the [[visual cortex]] will selectively use when looking at different distances.

== Measuring ==

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The '''power of accommodation''' is (near power) - (far power). With the first example in each of the above, it would be 10 D - 1.5 D = 8.5 D.

A person is generally considered to have presbyopia [[wikipedia:if and only if | iff]] his power of accommodation is less than 2.5 D.

===Caveats===

~~I’m not entirely sure how~~ cylinder ~~affects this measurement~~, ~~so you’ll have to refine the technique~~ if ~~you have cylinder~~.

This technique might need to be refined for cylinder, if spherical equivalent is not used.

The cornea and lens actually have more power because the total power has to focus the image on your retina, but they cancel out in the subtraction step, so it’s easier to ignore them.

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[[Category:Articles]]

[[Category:Eye conditions]]

== See also ==

* [[Varilux]] , Essilor progressive lens brand: the 1959 trial data, the Minkwitz constraint, and documented fall risk.

@@ Line 1: / Line 1: @@
-Presbyopia is the hardening of the [[lens]] in the [[eyeballs]] such that it becomes difficult to see [[near work]].  This is common in older adults and is commonly treated with [[reading glasses]] or [[bifocals]].
+Presbyopia is the hardening of the [[lens]] in the [[eyeballs]] such that it becomes difficult to see [[near work]].  This is common in older adults and is commonly treated with [[reading glasses]] (reduced minus for myopes), progressive lenses, or [[bifocals]].
+==Correction==
+As you age, the lens in your eye becomes less flexible.  This makes [[accommodation]] more difficult and brings on "arms are not long enough to read" symptoms.  Someone may be both [[myopic]] and presbyopic, and have deficits in both near and far vision.  Your [[Prescription]] will have an "Add" section specifying bifocals or multifocals if you have diagnosed presbyopia, or if your doctor thinks it best to reduce eye strain.
+===Two glasses===
+It is an option to have two pairs of glasses, one for close-up, and one for distance, instead of trying to combine both near and far corrections in one pair of glasses.
+===Bifocals===
+Glasses with a lower section that is specifically for close work.
+===Progressive lenses===
+Glasses with a gradient from zero to near plus addition spherical power from top to bottom.
+===Multifocals===
+Contacts that have sections for near and far work, which the [[visual cortex]] will selectively use when looking at different distances.
 == Measuring ==
@@ Line 15: / Line 30: @@
 The '''power of accommodation''' is (near power) - (far power). With the first example in each of the above, it would be 10 D - 1.5 D = 8.5 D.
+A person is generally considered to have presbyopia [[wikipedia:if and only if | iff]] his power of accommodation is less than 2.5 D.
 ===Caveats===
-I’m not entirely sure how cylinder affects this measurement, so you’ll have to refine the technique if you have cylinder.
+This technique might need to be refined for cylinder, if spherical equivalent is not used.
 The cornea and lens actually have more power because the total power has to focus the image on your retina, but they cancel out in the subtraction step, so it’s easier to ignore them.
@@ Line 34: / Line 51: @@
 [[Category:Articles]]
 [[Category:Eye conditions]]
+== See also ==
+* [[Varilux]] , Essilor progressive lens brand: the 1959 trial data, the Minkwitz constraint, and documented fall risk.